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George_45 Member Posts: 6
I had a no heat call last night. After I fixed the problem, I noticed the Tekmar ODR was set for a target temp of 150 but it kept heating to 197. The only thing I could think of is that it knows how cold the house is because of the no heat all day and it takes itself out of reset? The ODR is D420. Zone manager 336 and the thermosats are 5-42 and 5-41 ones a master the rest are all slaves. I meant to call tekmar today but I forgot to. Thanks.

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  • if it won't make it, it will keep raising its temperature to the max you have set. However, the target should show what it is trying to reach. if it's trying to reach 150 and it's going to 197, something's up. Maybe you have a permanent DHW call? That would go to max temp, not change your reset target, and cause a no heat call if you have domestic priority turned on..?
  • Randy Baerg
    Randy Baerg Member Posts: 26
    Reset target

    With the tN4 system the outdoor reset target does get modified by Indoor feedback. So if rooms are under heating the target will get boosted hotter. The control will display the new target and try to maintain this. Keep in mind that the Target has a split differential (1/2 Diff above target / 1/2 Diff below target) so the average supply temp delivered is the actual target. The differential also automatically adjusts to help prevent short cycling (between 2-42°F). So you could potentially see boiler up to 21°F (1/2 of 42)above target. Depending on where you observed temperature it could creep up after boiler shuts off.
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